In large scale electrical conductors, such as those used in the power generation industry, there are inherent problems in connecting electrical systems. One of the problems is that the electrical conductors will move independently of one another. This is due to the large scale mechanisms experiencing a difference of temperature, vibration or other environmental factors. If the connection point is rigid then the electrical connection wears rapidly and even breaks, which will cause shorts and other damage.
MLB assemblies have therefore been used to allow a difference of movement between two electrical conductors. One such type, typical in hydrogen inner-cooled generators, is shown in FIG. 1. In this figure, a first electrical conductor 2 is connected to a second electrical conductor 4 via a MLB assembly 6. The MLB assembly comprises a series of electrically conductive flexible connectors 8 that act as a flexible bridge between the two electrical conductors. Differences of movement between the two conductors 2, 4 can be readily absorbed by the MLB assembly 6.
Since large amounts of electricity need to pass through the MLB assembly 6, multiple flexible connectors 8 are used to attempt to spread the current evenly across the MLB assembly. However, what happens is that the current from one of the conductors 16 tends to pass in greater proportion to the outside flexible connectors 12, while little or no current passes to the inside flexible connectors 14. Therefore, the effective maximum current that this type of MLB assembly can carry is limited since increasing the number of flexible connectors 8 has a diminishing improvement on the current capacity of the MLB assembly. For example, in a MLB assembly using ten typical Penn Union™ 3″×8″×¾″ copper flexible connectors that have a maximum capacity of about 3000 amps, the entire MLB assembly will have a capacity of about 27,000 amps. Further, the flexible connectors on the outer edges of the MLB assembly wear proportionally faster than the other flexible connectors since they carry a greater burden of the electrical flow. This reduces the life expectancy of the MLB assembly and creates potential safety issues.
One technique for attempting to evenly spread out the current between flexible connectors has been to arrange the flexible connectors circumferentially, as shown in FIG. 2, instead of linearly. In this figure a MLB assembly 6 comprises a series of flexible connectors 8 that are evenly spaced circumferentially around a circular MLB assembly. Current passing from one conductor 2 to another 4 is now evenly distributed 18 among the various flexible connectors 8. This design, however, is still limited by the overall size restrictions of the MLB assembly. In other words, the MLB assembly can only be so large before it creates problems with the system design. The addition of extra flexible connectors necessitates the overall increase in the diameter of the MLB assembly. Therefore, the maximum current capacity of an 8-sided version of this type of MLB assembly using typical 3″×8″×¾″ copper flexible connectors is about 24,000 amps; which is less than the maximum current capacity of the conductors 2, 4 themselves, which may be upwards of 60,000 amps.
What is needed is a MLB assembly that evenly distributes electrical current among its component flexible connectors, and provides for an increased current capacity without significantly increasing the overall size.